Why do some friends and even family just spontaneously cut you out of their life without warning or reason ? Make excuses not to see you or to be busy and no matter how much you make the effort to see them or make contact - it is all futile...
People move on, there are times when a friendship has run it's course and not worth the effort it takes, e.g if they live or work some distance away. If someone doesn't contact me I reckon there are reasons for not getting in touch. I might possibly ring for a chat occasionally to keep in contact with them, but I wouldn't be too bothered about it.